Primary pulmonary hypertension: causes, symptoms, diagnosis, treatment

Primary pulmonary hypertension is a primary persistent increase in pressure in the pulmonary artery of unknown origin.

The disease is based on concentric fibrosis, hypertrophy of the media of the pulmonary artery and its branches, as well as multiple arteriovenous anastomoses.

The cause and pathogenesis of primary pulmonary hypertension are unknown. There are 2 hypotheses regarding the pathogenesis:

1. The disease is genetically determined and is based on a violation of the central regulation of vascular tone.
2. The disease is based on a congenital or acquired disorder of production of active vasoconstrictors: serotonin, endothelin, angiotensin II with increased platelet aggregation and formation of microthrombi in the microcirculatory bed of the lungs. Remodeling of the pulmonary vessels develops.

Yu. N. Belenkovi and E. Chazova (1999) distinguish 4 morphological types of primary pulmonary hypertension:

• plexogenic pulmonary arteriopathy - damage to muscular arteries and arterioles of the lungs (the process is reversible);
• recurrent pulmonary thromboembolism - organic obstructive lesion of muscular arteries and pulmonary arterioles; thrombi of varying age of organization;
• pulmonary veno-occlusive disease - proliferation and fibrosis of the intima of small pulmonary veins and venules, occlusion of precapillary vessels;
• Pulmonary capillary hemangiomatosis is a benign, non-metastatic vascular formation.

Symptoms of Primary Pulmonary Hypertension

1. The most typical subjective symptoms are a feeling of suffocation even with little physical exertion, rapid fatigue, sometimes chest pain and palpitations, fainting, and dizziness.
2. On examination: shortness of breath, pronounced diffuse cyanosis, absence of cough with sputum, changes in the terminal phalanges in the form of “drumsticks” and nails in the form of “watch glasses”.
3. Hypertensive crises in the pulmonary circulation are often observed (described in the article “ Pulmonary heart ”).
4. Objective symptoms of primary pulmonary hypertension are divided into two groups.

Signs of right ventricular myocardial hypertrophy:

• systolic pulsation of the right ventricle in the epigastric region;
• expansion of the border of cardiac dullness due to the right ventricle;
• ECG changes (see "Pulmonary heart");
• Radiological symptoms: protrusion of the outflow tract of the right ventricle - pulmonary trunk in the right anterior oblique position of the patient. As the degree of right ventricular hypertrophy increases, the inflow tracts also change, which leads to an increase in the height of the right ventricular arch in the anterior left oblique position. The ventricle approaches the anterolateral contour of the chest, and its greatest convexity shifts towards the diaphragm, the sharpness of the cardiophrenic angle decreases. Signs of cardiac dilation include an increase in the heart to the right and left, straightening of the cardiophrenic angles. Later, signs of an increase in the right atrium appear as a result of the resulting relative insufficiency of the tricuspid valve. The right atrium protrudes anteriorly above the arch of the right ventricle in the left oblique position, in the anterior position, an increase in the right atrium leads to an increase in the right transverse diameter of the heart;
• echocardiographic signs of right ventricular enlargement. With the development of right ventricular failure, the liver enlarges, edema and ascites appear.

Signs of pulmonary hypertension:

• accentuation of the second tone on the pulmonary artery and its splitting;
• percussion dilation of the pulmonary artery;
• diastolic murmur over the pulmonary artery caused by relative insufficiency of the pulmonary artery valves;
• On the chest X-ray - the protrusion of the pulmonary artery trunk, expansion of the main branches and narrowing of the smaller ones.

5. The final diagnosis of primary pulmonary arterial hypertension is based on the results of cardiac catheterization, pulmonary artery catheterization, and angiocardiopulmonography. These methods allow to exclude congenital heart disease, determine the degree of pulmonary hypertension and right heart overload, and state extremely high figures of total pulmonary resistance with normal pulmonary-capillary pressure. Angiopulmonography shows an aneurysmally dilated pulmonary artery trunk, its wide branches, and narrowing of the arteries of the peripheral parts of the lungs. Segmental branches of the pulmonary artery are as if cut off with a high degree of pulmonary hypertension, small branches are not visible, and the parenchymatous phase is not detected. The blood flow velocity is sharply slowed. Angiocardiography should be performed only in specially equipped X-ray operating rooms with great caution, since after the introduction of a contrast agent, a pulmonary hypertensive crisis may occur, from which the patient is difficult to recover.
6. Radioisotope scanning of the lungs reveals a diffuse decrease in isotope uptake.

Screening program for primary pulmonary hypertension

1. General blood and urine tests.
2. Blood biochemistry: protein and protein fractions, seromucoid, haptoglobin, CRP, sialic acids.
3. ECG.
4. Echocardiography.
5. X-ray of the heart and lungs.
6. Spirometry.
7. Cardiac and pulmonary artery catheterization.
8. Angiocardiopulmonography.
9. Radioisotope lung scan.

Treatment of primary pulmonary hypertension

Primary pulmonary hypertension is a disease of unknown etiology, characterized by primary damage to the endothelium, concentric fibrosis and necrosis of the walls of the pulmonary artery branches, which leads to a sharp increase in pressure in the pulmonary circulation and hypertrophy of the right heart.

There is no etiologic treatment. The main principles of pathogenetic treatment are as follows.

1. Limitation of isometric loads.
2. Active treatment of lung infections.
3. Treatment with vasodilators:
   • treatment with calcium antagonists (usually nifedipine, diltiazem). In the presence of sensitivity to calcium antagonists, 5-year survival is 95%, in its absence - 36%. If patients are sensitive to calcium antagonists, then with long-term multi-year therapy, an improvement in the functional class and reverse development of right ventricular hypertrophy is observed. Sensitivity to calcium antagonists is noted in only 26% of cases;
   • treatment with prostacyclin (a prostaglandin produced by the vascular endothelium and possessing a pronounced vasodilating and antiplatelet effect) - is used to treat primary pulmonary hypertension that is resistant to other treatment methods. Treatment with prostacyclin leads to a persistent decrease in pulmonary vascular resistance, diastolic pressure in the pulmonary artery, and an increase in patient survival;
   • Treatment with adenosine is performed with a sharp, even greater increase in pressure in the pulmonary artery system (the so-called crisis in the pulmonary circulation), adenosine is administered intravenously as an infusion at an initial rate of 50 mcg/kg/min, increasing it every 2 minutes to the maximum effective rate. The reduction in pulmonary vascular resistance occurs on average by 37%. Due to the very short-term, but powerful vasodilatory effect, a single administration of adenosine is safe and effective.
4. Treatment with anticoagulants (in particular warfarin, in an initial daily dose of 6-10 mg with a gradual decrease under the control of partially activated thromboplastin time) improves the state of the microcirculation system, increases the survival of patients. Treatment with anticoagulants is carried out in the absence of contraindications to their use (hemorrhagic diathesis, ulcer disease of the duodenum and stomach). There is a point of view on the greater expediency of treatment with antiplatelet agents (aspirin 0.160-0.325 per day for a long time).
5. Treatment with diuretics is prescribed in case of significant increase in pressure in the right atrium and manifestations of right ventricular failure.
6. Oxygen therapy is prescribed for severe hypoxemia.
7. In acute right ventricular failure, treatment is carried out with dobutamine at a dose of 2.5 to 15 mcg/kg/min: 10 ml of solvent (5% glucose solution) is introduced into a vial containing 250 mg of the drug powder, then everything is transferred to a vial with 500 ml of 5% glucose solution (1 ml of such a solution contains 500 mcg of the drug, 1 drop - 25 mcg).

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